Eurorack starter guide: getting into modular without overspending

Modular synthesis has a reputation as the most expensive hobby in music tech, and the reputation is mostly earned by the way people buy, not by the format itself. Eurorack is an open mechanical and electrical convention that hundreds of makers build to. That openness is the appeal: you can mix modules from anyone. It is also the trap, because there is no "finished" system and always one more module that looks like the missing piece.

This guide is for producers who already know what an oscillator, filter and envelope do (if not, start with our synth sound design basics) and want to try modular without a regretful credit-card statement. It is deliberately about method rather than a shopping list, since module catalogues change every month.

What Eurorack actually is

Eurorack is a size and power convention that grew out of Doepfer's A-100 system. Doepfer's construction details set the module height at 3U, 128.5 mm, and measure width in HP, where 1 HP is 5.08 mm. When someone says "a 104 HP case", they mean the usable width per row, and every module lists its own width in HP.

Doepfer's technical details page defines the electrical side: modules draw from +12 V and -12 V rails (some also use +5 V), delivered over a ribbon cable from a bus board, with the coloured (usually red) stripe on the cable marking -12 V. Pitch follows a 1 volt per octave convention, so one volt up on an oscillator's pitch input raises it by an octave.

Those three facts (3U height, HP width, ±12 V power on a keyed or striped ribbon) are most of what you need to know to avoid buying something that does not fit or cannot be powered.

Step 1: learn to patch for free first

Before spending anything, spend a month in VCV Rack, a free, open-source virtual Eurorack. In our view its real value is that the library includes modules modelled on hardware you can later buy, and the free collection is large enough to build complete voices, sequencers and effects chains.

Use that month to answer one question honestly: do you enjoy patching, or do you enjoy the idea of a modular system? If you find yourself reaching for presets and closing the app after twenty minutes, hardware will not change that. If you keep losing evenings to one patch, you have your answer, and you have also learned which module types you actually use.

Keep a note of every module you reach for in more than three patches. That list, not a forum thread, is your shopping list.

Step 2: decide what the system is for

A modular built "to do everything" is how people end up with three filters and nothing to drive them. Pick one job:

• A voice you play from your DAW or keyboard: oscillator, filter, envelope, VCA, a MIDI-to-CV interface.
• A drum and texture box: a few percussion modules, a clock, a mixer.
• An effects and processing rack for audio from your computer: filters, delays, a VCA, input and output level conversion.

One job means one small case, and it gives you a reason to say no.

Step 3: plan in a rack planner, not in your head

ModularGrid lets you lay out a virtual case with real module listings, sums the width in HP, and totals each module's current draw on each rail. Plan the whole first system there before buying a single module. You will catch two common mistakes: modules that do not fit the row, and a power supply that cannot feed them.

Check depth as well. Shallow "skiff" cases are popular and cheap, but some modules are too deep for them; module makers list depth in their manuals.

Step 4: respect the power budget

This is the part that costs money when it goes wrong. Every module lists how many milliamps it draws from +12 V, -12 V and (if used) +5 V. Add them per rail and compare against the supply's rating per rail, not its total. Leave headroom; running a supply near its limit makes it run hot and can introduce noise.

Then connect every ribbon cable with the coloured (usually red) stripe on -12 V at both ends, as Doepfer's technical page specifies. Many modules have reverse-polarity protection, but not all do, and a reversed cable is one of the most common ways beginners damage a module. Check each connection before you switch on, every time you add something.

Step 5: the first small system

A useful first voice, built in a small case, typically includes:

1. A MIDI-to-CV interface so your DAW or keyboard can play it. This is the module beginners forget, and without it the system cannot talk to anything else you own.
2. One oscillator you liked in VCV Rack.
3. One filter.
4. One envelope and one VCA, so notes start and stop.
5. A utility module: attenuators, a mult or a mixer. Utilities are unglamorous and they are what make the rest flexible.
6. An output module or a line-level route into your audio interface.

Buy used where you can. Eurorack has an active second-hand market because people reshuffle systems constantly, and a module that works is not worse for having had an owner. Stop there for at least a month.

Step 6: integrate with the computer you already have

Your laptop is already a sequencer, a recorder and an effects rack. Let it do those jobs. Sequence from the DAW through MIDI-to-CV, record the modular to audio, and process it with plug-ins you own. If you play live, our guide to a live setup for electronic artists covers how to fold hardware into a set without it becoming a single point of failure.

What we think

The modular world sells itself on infinite possibility, and for artists that framing is backwards. Constraint is what turns a pile of modules into a sound people recognise as yours. The most distinctive modular records tend to come from small systems played deeply, not from walls of panels, because limits force you to learn each module's quirks until they become your vocabulary.

So we would push a different question than "what should I buy next". Ask what your current system cannot do that a specific song needs. If you cannot name the song, you do not need the module. That test protects your money, but more importantly it protects your attention, which is the scarcer resource.

We also think the software-first step is underrated as artistic practice, not just as a free trial. Patching in VCV Rack, where modules cost nothing, shows you quickly whether your ideas are limited by gear or by habits. For most people it is habits, and no hardware fixes those. When hardware does earn its place, it is usually for the hands-on feel and the happy accidents of real circuits, which are good reasons, as long as you are honest that they are the reasons.

Finally, the format's openness is worth defending as a choice. A system built from a shared standard can be sold, rearranged or handed on, module by module. That makes Eurorack one of the few corners of music tech where you are not locked to a single company's roadmap, and that is a better argument for it than any single module.